System and process for the remote control of selectors or similar units



Dec. 6, 1949 Filed Aug. 6, 134'? F. P. GOHOREL 2,490,048

SYSTBI MED PROCESS FOR THE REMOTE CONTROL 9F SELECTORS OH SIMILAR UNITS.

3 Sheets-Sheet l INVENTOR FERN/4ND P/f/PlPf GOHO/PEL WwyL ATTORNEY 6,1949 F. P. GOHOREL SYSTEM AND PROCESS FOR THE BEMOTE CONTROL orSELECTORS on sum. mum's Filed m. s. 1947 s Sheeizs-Sheet 2 L RE Wm NE W4 m M A N m F ATTORNEY 1949 F. P. oHaRE'L SYSTEM AID PROCESS FOR THEREMOTE CONTROL Filed Aug. 6, 1947 T3? SELECTORS OR SIMILAR UNITS 3Sheets-Sheet 3 s sh Ei o o o W 0 o o --:0 o 0 III ATTO R N EY PatentedDec. 6, 1949 SYSTEM AND PROCESS FOR THE REMOTE CONTROL UNITS OFSELECTORS OR SIMILAR Fernand Pierre Gohorel, Antony, France, assignor toInternational Standard Electric Corporation, New York, N. Y., acorporation of Delaware Application August 6, 1947, Serial No. 766,692In France November 6, 1945 Section 1, Public Law 690, August 8, 1946Patent expires November 6, 1965 Claims.

The systems are well known in which a selector may be directed, from aremotely located control device, to a given position (or group ofpositions).

To this end, the selector is equipped with a set of marking contactswhichare scanned by a suitable scanning device, each position (or eachgroup of positions) being characterized by a potential, the nature of acurrent or the phase angle of an alternating current applied to thecorresponding marker contact. Means also are provided for the rotationof the selector to continue until such time as there exist a givenrelationship between the electrical condition of the marker contact andthat of the control or directing device.

It is quite obvious that where'the number of positions (or of groups ofpositions) is a large one, it becomes difiicult to secure, for themarker contacts, such electrical conditions as lend themselves to simpleidentification. This had led to the use of electronic means,endowed withgreat sensitivity, but at the same time difiicult of construction andcritical of maintenance.

On the other hand, it is well known that, in a general sense, anelectromagnetic relay of suflicient sensitivity to attract its armaturewith great rapidity does not release it with the same speed when itscircuit is opened, this delay upon release becoming more substantialstill when the current passing through the relay, instead of falling toa zero value,- merely assumes a magnitude smaller than that of relayenergization or operation.

Under such conditions, any relay which attracts its armature in theselector positioning unit, during the scanning of the marker contacts,while the scanning or hunting member passes on a position (or group ofpositions) at which the selector is not supposed to stop, will notimmediately drop its armature as the scanning member leaves the position(or group of positions) just alluded to. Furthermore, if the speed ofsaid device be of sufficient value, which is prac tically the case ofselectors, such a relay thus may cause false positioning during thescanning of the following marker contacts.

One of the characteristics of the invention will be found in the factthat the marking potentials are so arranged that, bearing in mind thescanning order of the corresponding marker contacts, it be not necessaryto energize any relays upon passing the position (or group of positions)which precedes the one at which the selector must be stopped.

A process for the adjustment of a selector having n positions (or 11groups of positions) in ac-:

cordance with the above mentioned characteristic is obtained by thefollowing combination in which:

1. Use is made on n1 sources of direct current at the same potential u,series connected, which gives n potential levels or steps.

2. If the n marker contacts of .11. positions be designated by l, 2, 3,4'. n, counting in the order of their scanning, they are connected tothe potential steps according to the following rule: contact I to 0potential, contact 2 to are rounded off to the nearest integer below theactual figure obtained.

3. A provision is made, in the directing or orienting device, insertingthem in the directing or control circuit, for two series or parallelconnected relays, the first of one is capable of attracting its armatureat a potential difference equal to 11 while the second, or marginal one,is capable of attracting its own armature only for a potentialdifference of 2a. Said relays are connected, on the one hand, with thescanning device of the selector marker contacts and, on the other hand,with a potential lever l or step which depends on the position at whichthe selector is to be stopped, provisions being made for them to beenergized only by a current circulating in a given direction.

4. Scanning of the selector is caused throughout the time during which,either the first relay is not attracted, or both simultaneously attracttheir respective armatures.

Another process which is an application of the characteristic indicatedabove and which makes 9...; 1. Use is made, for the marking of n groupsof positions, of 1; sources ofdirect'current,

of which have their negative'term-i-nals connected to a common point,while the'remaining common point. The voltages of the positive sourcesare all different from one another but may be respectively equal to thevoltages of the negative sources. One thusiprovides 2 steps of positivepotentials and steps of negative potentials.

2. The

groups are connected to the negative (or positive) potential steps orlevelsFWhere n is odd, two consecutive groups of marker contact groupsare connected to two positive *(or negative) steps in such a manner thatthe step having the lower voltage precedes, in the direction ofscanning, the one having the'higher voltage.

3. A provision is made, in the controlling or directing device, forseveral relays connected either in series or in paralleland capable ofoperating only with a given direction of current, the armatureattraction or .-nonattraction of .said relays being dependenton-thepotential difference applied to their terminals. These relays areconnected, on the one hand, to the scanning device of the selectorand,on the other hand, to the common .point of all the current sources andthe current direction for which they are attracted, as well as theirattraction .or non-attraction'combinations, depend .onthe group of linesor-on the line to which the :selector is to be dirooted.

4. Scanningof the selector and its positioning are controlled accordingto the attraction ornonattraction combination of 'th'e'relays of thep'ositioning or direction device.

In the process outlined above, the common point of the current sources,aswell as one of the terminals of therelay 'group' may be grounded,which does away with the need for a connecting wire between" theselector and thedirecting device. This arrangement is of particular'advantage when the selector and'the directing device are not installed.in ais'ingle room (such as is the case, for instance, in'telephonenetworks having several central oifices) 4 Another process, according to.the characteristic of the invention, "which makesit possiblesubstantially to reduce the number of the potential steps, and thus theprecision needed in the operation of the control relays consists, incom- 1 bination with-the processes discussed above, of the following:

have their positive terminals connected -to said 1. Analternating'current source or several alternating currentsources havingdifferent voltages or frequencies are connected in series with -rentmarking potentials, the superimposition of a single alternating currenton each direct current source will provide 211. marker steps, while,with twos'ourceisoi alternating current, the number of-marker stepswould be raised to 3n.

2. The marker contacts of the selectors, in their order of scanning, arealternately connected to a direct current potential step and to apotential step obtainedby means of the superimposition-of thealternating current source on the direct current source used for thepreceding marker contact. The order of the direct potential stepsischosen in the manner which has been outlined above with relation toanother process. In cases where several alternating current sources areavailable, the various potential steps obtained by thesuperimpositionfto a direct current,'of each one'of the alternatingcurrent sources, are connected'in succession to a series of the selectormarker contacts before another direct current potential level isconnected. to the next contact in line.

3. Scanning'of these'lector and'its'position are controlled by theaction of 'relays which are responsive, not 'only"to direct current, butalso to alternating current.

In combination with theabove outlined processes, it is possible further"to increase the number ofthe positions which can be assumed by theselectors, when't'hey are equipped with a drive mechanism of "thestep-bystep type, and when call'number'reg'istered by the controlling ordirooting-device. Such,for-inst'ance, is the case oi the line selectorsor final selectors used in automatic switching "telephony.

According to the "inventiomthe selector is divided into groupsyeach ofwhich comprises a certain number of positions, the first of which inturn is marked by a potential level or step, and to which the selectormay be directed or positioned by the controllingor directing device inaccordance with one of the processes which have already been describedabove. When this preliminary positioning' or directing has beencompleted, the controlling or directing device sends out "as manyimpulses asare'needed to cause the selector to 'movea'he'ad'to the finalposition to 'which it is tobe directed. The controlling or directingdevice of the'selector is placed in series; for thepreliminarydirection, with-a rectifier which passes only one currentalternation and a sourceof alternating current'while, for the finalpositioning or directing, itis connected to an imp-ulsing contactandasource of direct current.

Various'embodiments of the processes outlined, in'a'ccordance with theprinciples of the invention, will no'w'b'e described as non-restrictiveexamples/in relation with the appended figures. These figures show onlysuch circuit elements as are necessary for an understanding .of theinvention.

In the directing process of Figure 1, two relays A and B are provided indirecting device 0. These relays'are inserted in a circuit which isconnected, on the one hand, to the scanning device of selector S, namelywiper F and, on the other hand, to unilaterally conducting elements Q1and Q2. According to the number received by the controlling or directingelement, one of contacts sal to $115 is closed. Relay A can attract itsarmature when there is a potential difierence equal to u and relay B canattract its own armature only when such potential difierence as ispresent is equal to Zn.

Marker contacts l to 5 of selector S are connected as shown on thefigure.

It will now be assumed that contact sa3 is closed, namely that selectorS must be directed to position 3. When director and selector S have beenconnected, the circuit of drive electro-magnet R is closed through restcontact al of relay A. When wiper F reaches the third position, thefollowing circuit is completed: negative polarity on Us at contact 3 ofS, wiper F, relays A and B in series, unilaterally conducting elementQl, closed contact sat and positive polarity on battery U3. Relay Aattracts its armature and relay B remains at rest. Through its restcontact al, relay A opens the circuit of drive electro-magnet R. andselector S stops at the third position.

Through its work contact al, relay A completes, by way of rest contactbl of B, the circuit of relay C, which causes, in the directing orcontrolling unit, the operations which follow the stopping of theselector.

The case will now be taken up of the possibility of false positioningwhen wiper F passes on bank contacts 1 and 2.

When wiper F passes on bank contact I, the

following circuit is completed: negative terminal of battery U4, contactI and wiper F, series connected relays A and B, element QI, contact sa3,positive terminal of battery U3. Since the two batteries, U3 and U4 areconnected in series in the circuit relays A and B will attract theirrespective armatures. Through its work contact b2, relay B completes thecircuit of R, which is open at al. Selector S thus will continue thescanning motion. Through its contact I), relay B makes a break in thecircuit of C and this last mentioned relay can not be energized.

When wiper F passes on position 2, the positive polarity of U2 is placedon said wiper. The circuit of relays A and B cannot be completed due tothe fact that element Q2 is not placed in the circuit. Relays A and Bdrop their respective armatures and S continues the scanning.

It will be observed that relay B, which had been energized at position1, drops its armature at position 2 or, in other words, there is no needfor any energized relay at the position which precedes the one to whichthe selector must be directed. By having reference to the directing orcontrolling circuits, it will readily be seen that stopping is effectedby the energizing of relay A, at position 1, through Ql (U4); atposition 2, through Q2 (U2) at position 4, through Q2 (Ul and atposition 5 through Ql (U2). Furthermore, there can be no falsepositioning.

Figure 2 shows a variation on the process of Figure 1, which makes itpossible to reduce the number of the wires needed between the direct ingor controlling unit and the selector.

A certain number of batteries U3, U2, Ul, U'l, U2, etc. are arranged inselector S, having the same voltage u and connected in series, thecommon point between batteries UI and U'l being grounded. Thisconstitutes a certain number of potential steps or levels, namely 6 inthe example under review, which are respectively equal to 3u, 2u, u, 0,+u and +2u. The negative potential steps or levels are connectedrespectively to the bank contacts associated with wiper F of selector Son odd positions 1, 3 and 5, while the positive potential steps orlevels are respectively connected to positions 2 and 4.

It will now be assumed that contacts sa3, sb3, s03 are closed, namelythat the selector has to be directed to position 3.

' As soon as directing device 0 is connected with the selector S to bedirected, the following circuit is completed: battery, electro-magnet R,contact s03, rest contact al associated with relay A, ground.

Electra-magnet R then causes, according to a well known process, theprogression of its wipers in automatic rotation. When said wipers reachposition 3, the following circuit is completed: negative terminal ofbattery U2, bank contact and wiper F at position 3, unilaterallyconducting element Q2, contact sa3, left hand windings of relays A and Bin series, ground and, in selector S, ground and the positive terminalof battery Ui.

Relay A has been so designed that it attracts its armature only in thepresence of a voltage equal to 2u at least, if it is energized on itsleft hand winding and to u if it is energized on both of its windings.Similarly, relay B has been so designed that it is energized by avoltage equal to Bu at least, if working on its left hand winding and21L if working on both windings. Relay A thus will be the only one toattract its armature, since the above outlined circuit closes throughtwo batteries, each of which has an E. M. F. equal to u; it opens, atal, the drive circuit of the selector and completes, by way of its workcontact a2, the following circuit: battery, relay C, contact sb3, workcontact a2, rest contact 132 associated with relay B, ground. Relay C isenergized and causes, within the directing or controlling unit; thevarious operations which follow, the stopping of the selector.

Even as was the case with the arrangement of Figure 1, let us now reviewthe possibility of false positioning when Wiper F passes on positionsother than position 3. When it passes position 1, the following circuitis completed: negative terminal of battery U3, bank contact and wiper Fat position 1, unilaterally conducting element Q2, contact sa3,left-hand winding of relays A and B, ground and, in selector S, groundand positive terminal of battery UI. Relays A and B are both energized,due to the presence of a potential diiference 32L; at al, relay A makesa break in the drive circuit of the selector but, by way of its workcontact bl, relay B restores continuity to said circuit and the selectorcontinues its progression. Relay C being of the delayed attraction type,remains at rest, even if its circuit has temporarily been completed atb2 and a2, due to the non-simultaneity of the operation of relays A andB. When the selector passes position 5, relays A and B, the circuits ofwhich are completed only through battery Ul, remain at rest and theprogression of said selector continues. When the selector passes evenpositions 2 and 4, batteries U'I and U'2 are the ones to intervene, butthe circuit of relays A and B can not be compl ted :clueo the.presencaoi nle laterally conduc in I elemen Q2.

It will be observedtbat r lay e ergiz d at. Position 1; has allhe-needed time tor piti armature t posit-1on2. thisdoes notp e risl; ofbeing. held at position 3, which would make it impossible for the.selector -to,-stop.

A study of the various directing rc ntrollin circuits will show thatstoppin isscaused ,bythe energizing of. relay. .A,1'at position, throughbate tery l. r fi r-:Ql'andthe two series: connectedwindingszof.Aaatposltio l; throu h UZzi and Q l, .at position .5,through. U1 andaQZ. False positioning is made impossible-due tothe factthat, on the even numbered positions, the circuit'of relays A and B canbe completed only if the directing or. controlling unit is on anoddnumbered position due to; the presence jot-one of the two unilaterallyconducting elements. QI- and. Q2 and conversely. .On the. other. hand,when rectifiers 6.2!. and Q2 do not oppose he passage of current, thevoltage is either. too weak, which makes itimpossible for relay. A..tobe energized, or too high, which causes relay B to be energized and theprogression of the. selector to.

continue.

When the selector has to be directed .to position 1, contactssal, sbl.,.scl are closed, thedrive circuit passes through: battery, electroemagnetR, contact scl,.rest contact bl,.ground, stopping being effected byrelay B, which is:ener ed through. batteries. U1, U2, U3, rectifier Q2and contact sal. The circuit. of relay C then is com pleted through b2and sbl. False position ng or directing is impossible for the veryreasonswhich have been discussed in the above paragraph.

Figure 3 shows a device which makes it pos sible to direct a selector to211. positions by making use of only 11. batteries,

of which (Ul, U2, U3) have theirpositive tep minal connected to a commonpoint which is grounded in the example illustrated, and'the other ofwhich (U'l, U2, U'3) have thelrrnegative terminal connected to saidcommon point. The

voltages of batteries Ul, U2, U3 are'different from one another but mayrespectively be equal to those of batteries U l, U2, U3. In order to.make mat ters clearer, let ul, a2, a3, u I, u2, u3 be. the respectivevoltages of batteries Ul, U2, U3, Ul, U '2=,' U'3 with:

The negative terminals of-batteries U1, U2, U3 are respectivelyconnected to positions 1, 5 and 9 of selector S while the positiveterminals of Ul, U2, U'S are connected to positions 3, 7 and 11. Eacheven numbered position is connected to the odd position whichimmediately. precedes; it through an alternating current generator whichmay, by way of example, be one of the windings of the secondary of atransformer T. Rela Ahas been so designed as to attract its armaturewith a voltage equal at least to a2, if its left-hand wind ing is theonly one in the circuityand with a voltage equal to 11.3 at least, ifbothwindingsare functioning. Relayv B has been designed to at? tract itsarmature for avoltagesequalto uliat' least if its leftrhand' wind n sthe. only o e n the circuit and for a voltage equal at least to a2.ifboth. windingsare in the, circuit,

Let it be assumedthat the selector must be directedto-position 5;contacts m5, sb5, s05, sd5, set, of the directing or controlling element0 then are. closed. 'Assoon as said controlling unit is connected toselector S, which is to be directed or positioned, :the. followingcircuit is completed: batteryadrive electro-magnet R, contast s05, restcontact a! associated with relay A, ground. The drive electromagnet Bcauses the selector wipers to move ahead in automatic rotation. Whensaid wipers=reach position 5, the following circuit is completed:negativeterminahof battery U2, bank contact-andwiper F- of the selectorat position 5,

unilaterally ,conductingelement Ql, contact sa5, leftehand windingsofrelays A nd B. conn c in series, ground; and, in, selector r un dpositivev terminalqofy battery U2. The voltages needed to energize;relays A and B on the left-hand winding are, respectively, a2 and ul, sothat relay A is the only one to attract its armature, closing :at: a2the vfollowing circuit of relay C: battery, relay C, restcontact (12,associated with relay D, contact 3225, Work contact o2, rest contact122.. associated with relay B, ground. Relay C is energized causing, inthe directing or controlling unit,.the various operations which followthe stopping of the selector.

.Itisimpossible for. said selector to stop on any position but thefifth. It we take position 1, we see-that battery U5 is the. one tointervene so that relay Bis energized at the same time as relay A andcauses, through its work contact bl, the re-starting of the selector. Atposition 9, battery U3 is. placed in the circuit and relay A itself isunable to become energized with the flux generatedby. its left-handwinding only. At positions 3, 7. and .11., batteries U l, U'2 and U'3are the ones placedinthe. circuit; relays A and B can not beenergizeddue to the presence of'unilaterally conducting. element Q1. Atpositions 2, 4, 8, 10, 12, false positioning is ruled out for motivesidentical to .those whichoppose stopping at the odd numberedpositionwhich immediately precedes them. The. alternating currents generated bywindings tl to t6 willbeso chosen as not to cause unwanted operationof'relays A and B. At position 6 which immediately follows position 5.,or the stopping position, the following circuit is completed: negativeterminal ofbattery U2, winding t3, bank contact and wiper F at position6, unilaterally conducting element QLcontact sa5, left-hand Windingofrelays A and B, ground and, in selector S, ground and positive terminalof battery U2, winding t3, bank contact and wiper F at position 6,workcontactaS, contact se5, capacitor 0, bridge rectifier such as madeupof elements Q3 to Q5, ground. .Relay D is energized due to the effect ofthe rectified current and completes, by way of its work. contactsdl andsd5, the drive circuit of the selector, which otherwise-would be open atat; .by the opening of its rest contact d2, it opposes the unwantedenergizing of relay C. It will be noted that, according to theinvention, none of relays A, BandD has its circuit completed at position,4 of'the selector, which immediately precedes stopping position 5.

It-will now be assumed that. the selector has to be directed to an evennumbered position, position 6 for instance. Contacts safi, sbfi, s06,sdfi, sefi, are closed. When the selector moves on to position 6, thefollowing circuit is completed: negative-.terminal'of battery U2,winding t3, bank contact and wiper F of the selector at position 6,unilaterally conducting element Ql, contact sat, left-hand winding ofrelays A and B, connected in series, ground; and, in selector S, ground,positive terminal of battery U2 with, in parallel across the circuitoutlined above, contact seB, capacitor C, relay D through bridgerectifiers Q3 to Q6, ground. Relay A is the only one to be energized, tothe exclusion of relay B, for reasons explained elsewhere; thealternating current, on its side, causes the operation of relay D, afterits rectification by bridge rectifier Q3, Q4, Q5, Q6. The drive circuitof the selector is open at al and dl. Relay C is energized by way of:battery, relay C, work contact d2, contact sbli, work contact (12, restcontact b2 and ground.

No false positioning is possible; at positions 1 and 9, the voltage issuch that relays A and B both attract their armatures or both remain atrest. On positions 3, 7 and 11, rectifier Ql makes it impossible forrelay A to be energized; at positions 2, 4, 8, 10, 12, the reasons whichmake it impossible for the selector to stop are the same as those whichrule out stopping at the odd-numbered positions which immediatelypreceded them; at position 5, which immediately precedes the stoppingposition, the drive circuit of the selector is completed through restcontact dl, associated with relay D and edit.

Study of the various directing circuits will show that stopping of theselector is effected at position 1, by the energizing of relay B throughits left-hand winding, through battery UI and rectifier Ql, at position3, by the energizing of relay B on its left-hand winding through Ul andQ2, at position 5, by the energizing of relay A on the left-hand windingthrough U2 and Ql, at position 7 by the energizing relay A on itsleft-hand winding through UZ and Q2, at position 9, by the energizing ofrelay A on both of its windings through U3 and Ql, on position 11, bythe energizing of A on its two windings through U'3 and Q2. At anyeven-numbered position, stopping is effected as at the odd numberedposition which immediately precedes it with, in addition, the energizingof relay D.

It will also be noted, generally speaking, that the selector can notstop at a position different from the one required; either the directionof flow of the current is such that neither relay A nor relay B can beenergized and rotation is continued through rest contacts al and bl, orelse the battery tension applied to the circuit is too high, whichcauses relay B to be energized and the rotation of the selector tocontinue by way of work contact bl; or else the voltage of the batteryplaced on the circuit is too low, neither of relays A and B being ableto attract their respective armatures and rotation being continued byWay of cl or bl, or again the position'on which the selector is even,rather thanodd numbered, which causes relay D to be energized throughone of contacts a3 or b3 and the rotation of the selector still tocontinue through work contact dl; or, finally the position passedby the.selector is odd, rather than even numbered, in which case relay Dremains at rest and causes rotation to be continned by way of its restcontact dl.

It will also be seen that, according to the invention, no relay whichmight cause unwanted rotation has its circuit completed at the positionwhich immediately precedes the stopping position, neither relay A norrelay B, due to the presence of unilaterally conducting elements Ql andQ2, nor either relay D, due to contacts a3 and b3.

It has been assumed, in the above discussion, that the voltages ofbatteries Ul, U2, U3 were respectively equal to those of batteries U'l,U2, U3. It is obvious that this condition is not by any meansindispensable and that the voltage of battery U'l, for instance, may besmaller than that of battery Ul, provided there be a suflicient marginbetween said voltage and the one immediately smaller, namely a2 or u2.

Figure 4 shows a directing or controlling device which embodies acombination of the processes described above and the process wherebydirecting is effected through the sending out of impulses. The selectorillustrated comprises a certain number of positions which are grouped intens; for the clarity of the illustrations, only tens numbers 1, 2 and 3have been shown, as well as only the four first positions of each ten.The first positions of each ten, say 10, 20 and 30, are connected tobatteries U3, U2, Ul U I, UZ, which are arranged similarly to the mannerin which they are shown in Fig. 2, although any one of the abovedescribed processes might be used, while the bank contacts associatedwithwiper F at the other positions are insulated. The control unit 0 maybe similar to that shown in Fig. 2 except that the electro-magnet R. isnot selfinterrupting and is connected to ground, that the armaturesassociated with contacts al and bl are connected together and through aunilaterally conducting element Q1 and generator GeZ to ground, and thatthe lead connected to the electro-magnet R is also connected to the workcontact z'l of a relay I, the associated armature being connectedthrough 'a battery Ui to ground.

It will be assumed, by way of example, that one has to direct selector Sto position 23. When said selector is connected to director or controlunit 0, the following circuit is completed: ground, drive electro-magnetR of selector S, contacts s02,

'rest contact al, associated with relay A, unilaterally conductingelement Q1, generator GeZ, ground. When the selector reaches thefirst-position of the required ten, position 20, in the example underreview, contact al opens. in Fa similar manner to that described inconnection with Fig. 2, contact bl is not energized, and the selectorstops. Thereupon the relay I is operated and released three times, inthe example given, by means not shown, so as to cause contact il toclose three times in succession, and three direct current impulses,supplied by battery Ul, are sent to electro-magnet R, causing it to moveahead to position 23. f

It is quite obvious that the devices described above have been givenonly by way of example and that it would be possible, without therebyexceeding the scope of the invention, to increase the number of thepositions to which the selector can be directed, by the device ofproviding a greater number of batteries, and a whole range ofalternating currents differing from oneanother by their amplitude, theirfrequency or their phase g I claim: 1. In a selector system, a selectorswitch comprising a test wiper, a plurality of test terminals, andelectric driving means for said switch, a plurality of potential sourcesconnected to said test terminals, a first test relay. having contacts inthe circuit of said switch driving means and adapted to operate at apredetermined voltage, a second test relay having contacts in thecircuit of said switch driving means and adapted to :cperate' atapredetermined diiferent .voltage, the saidrelay contacts being arrangedso that the voperationaof one .of: saidrelays without the otherwilldeeenergise the :switch sdriving means, while :then operation...of.both relays will not break the .icircuitfofsaid switch driving means,and marking .meansincludinga pair .of..contacts .for each testterminal-10f said switch .and unidirectional current devices formarkinga position of the .switch IOISBIECtiOIL'thE windings of said relays andsaid :marking means being. serially connected between saidztest wiper.and saidrpotential' sources, the

-'connection-between.said'marking means and said sources being over alesser number of leads than there, are test terminals.

2. In a selector system, the combination according 1170 claim 1, inwhich there are two uni- =.dir'ectional devices, one; connected inseries with certainwof said marking contacts and the other connected ina reverse direction in series with.

certain other-ofsaid marking contacts.

, 3.;In1a selector system; acombination accord- -:ing.;. to..claim: -2in: which the sources of potential are *connectedtogether-in series.

-4..In.ia selector. system, -.the combination ac-.

cording tozclaimfl, in.which the markingmeans is .:connected' :by: atleast-"one lead to a junction point-between two ofsaid sources.

5.-In a selector system, the combination according to claim 1, in whichthere are two unidirectional devices, one connected inseries withcertain of said marking contacts and the other connected :areversedirection in series with .certainother of said marking contacts,and in which-said sources of potential are. connected togetherain seriesand certain .of said marking contacts are connected to the.junctionpoint he- .tweentwo of -saidsources while certainwother-of saidmarking contacts'are connected-toztheijuncation-qpoints .between others.of said-z-potential'.

sources;-

-6. In aselectorv system the combination .ac-

cording-to. claim-'1, ,in which two" unidirectional devices areprovidedoneconnectedin series with certainpf saidmarking contacts andthe other connected in the .reverse direction :in series with certain.other ofrsaid. marking contacts, said potential sources being. connectedtogether in. series, =and:.in.-.which saidtestrelays'are each providedwith; two windings, certain of said marking contacts .being arranged toconnect one. winding of each relay in series :while certain other ofsaid :inarking contacts :being arranged to connect all oi-saidwindingsin series, there. being 'a single wire connecting said markingcontacts'with a junction point between two of said potential sources andin which additionalmarking contacts are provided forreversing theoperation of said relayswith respect to said switchdriving 7. Inaaselectorsystem, the combinationaccording toclaim 1 in which thepotentialsources .are all connected toma common point, and .in

which; two unidirectional devices are provided,

one connected in series with certain of said mark- .ing contacts andtheother connected in the-0pposite direction with certain other ofsaidmarking contacts, and in which the test relays are each providedwith two windings, the connections being such that certainof saidmarking contacts connect one winding of each relay in series whilecertain otherof said marking contacts connect all of saidwindingsinseries, there being a single connection between said commonpoint and said marking contacts, and .in .whichiadditional marking'contacts are provided toreverse the operation of saidtest relays withrespect to said switch driving means, and in which .is provided aplurality of potential sources having different characteristics fromsaid first-mentioned potential sources, certain of said test terminalsbeing connected to one of said first potential sources and one of saidsecond potential sources in series, a third test relay connected betweensaid test wiper and the common point on said first potential sources,said relay being under control of said first and second test relays,means for making said third test relay responsive only to one of tionalcontrolling means is provided responsive only to said alternatingcurrent sources for further controlling the switch driving means wherebythe number of test terminals may be increased.

9. In a selector system, the combination according to claim 1 in which athird relay is provided under the control of the first and second testrelays for performing an operation when the selector switch comes torest at the desired position.

10. In a selector system, the combination according to claim 1, in whichthe connections between the sources of potential and the test terminalsand the connections between the relays and the marking contacts are suchthat neither 'of said relays is operated when the wiper of the selectorswitch is on a test contact immediately preceding the marked position.

FERNAND PIERRE GOHOREL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name. Date :Re 22,799. iDeakin. Oct. 1,1946 2,376,346 De akin; -May 22, 1945 2,423,078 Vriendt July .1, 19472,424,585 Simon July 29, 1947

